Ahead Of Wildfire Season, Scientists Study What Fuels Fires

A lab technician lighting a fire in a wind tunnel at a fire lab in Riverside, Calif.

Sean NealonUniversity of California, Riverside

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Originally published on May 10, 2014 4:00 pm

As fire managers in the drought-stricken Southwest gear up for another long and expensive wildfire season, federal fire scientists are trying to better understand the physics behind what makes blazes spread.

At a U.S. Forest Service fire lab in Riverside, Calif., a team of scientists is conducting daily experiments over the next few months on different fire behavior conditions. They hope to hand off their findings to fire managers, who have to make the quick decisions on where to deploy resources that could protect lives and property.

The centerpiece of the lab is a 30-foot-long, 10-foot-high wind tunnel and inside is a layer of wood shavings meant to mimic a dry, forest floor. Above them, resting on a shelf, are freshly picked green shrubs, the live green trees in this soon-to-be simulated forest fire.

That's the signal for another fellow tech to turn on the wind and light a fire in the dead wood shavings. Just like that, there's ignition and the lab smells like campfire. With a little more breeze, suddenly it's more like a bonfire. The ground fire easily jumped to the live green shrubs, which are surprisingly flammable.

The lab is blazing hot and ash is falling everywhere, enough so that David Weise, the lead research forester, has to shield his eyes and back away from the wind tunnel.

"That elevated canopy looks to be burning with flames on the order of eight to ten feet," Weise says. "Even though it's green, it's really burning quite well."

After all, these are the plants that blanket the chaparral hills of Southern California and Arizona, notorious for fueling some spectacular wildfires. But what Weise wants to know are the precise conditions that turned this small blaze into a potentially large one; one that would be almost impossible to control in the field.

"What we're trying to do here is conduct these experiments so that we can produce models, which can be used to perhaps predict what might happen under conditions that might be outside of a manager's experience," Weise says.

Weise says that with improved models of fire behavior, that fire manager will have a better idea where to put resources to get out in front of the fire. His team plans to conduct these daily experiments under all types of different wind speeds, humidity and types of fuel for a couple more months.

There is a sense of urgency with research like this. It turns out that most of the fire behavior models commonly in practice today are based on research conducted 40 years ago. And there's no indication that wildfires are going to get any less severe anytime soon.

Most of those outdated models are also based on what a fire does in dead or dry fuels, not live fuels, according to Tim Sexton, a former incident commander who's now with the National Inter-agency Fire Center in Idaho.

"If you have very specific understanding of the live fuel moisture, that may make the difference," Sexton says.

Sexton says research that could help fire managers do their jobs better has never been so important. Firefighters are encountering more dangerous blazes as the West experiences larger and more intense fires due to drought and the spread of development into the woods.

Copyright 2014 NPR. To see more, visit http://www.npr.org/.

Transcript

ROBERT SIEGEL, HOST:

Severe drought is gripping much of the southwest. As a result, another long and expensive wildfire season is expected. Federal fire scientists are trying to better understand the physics of how fires spread. As NPR's Kirk Siegler reports, they hope to hand this research off to fire managers who have to make quick decisions on where to deploy resources to protect property and lives.

KIRK SIEGLER, BYLINE: If you're an incident commander or say a crew boss on a large wildfire, you're in charge of coordinating a lot of things at once.

UNIDENTIFIED MAN #1: A dozen engines, three people each, a couple safety officers, taskforce leaders and (unintelligible) so you're looking at almost 200 people just in this couple mile stretch.

SIEGLER: Take last summer's massive Rim fire in Yosemite National Parker.

UNIDENTIFIED MAN #2: Do they need help up there?

UNIDENTIFIED MAN #1: (Unintelligible) half hour (unintelligible) .

UNIDENTIFIED MAN #2: Is the crew up there though?

UNIDENTIFIED MAN #1: No, it's just the two (unintelligible) .

UNIDENTIFIED MAN #2: Oh, it's just them?

UNIDENTIFIED MAN #1: Yeah.

SIEGLER: On the frontlines fire managers have to decide where to deploy hundreds of firefighters and when, and depending on the wind and visibility whether to do it by ground or air. These are split-second decisions based on the best available data and fire behavior models, and sometimes not so technical things like a manager's prior experiences or instincts.

(SOUNDBITE OF WORKFORCE)

SIEGLER: The forest service, the lead federal agency for firefighting, is studying how to improve forecasting and better predict a fire's behavior. What are the exact conditions that cause a blaze to go from a small ground fire to one like this in Yosemite, crowning in the big green trees, spreading fast and threatening a lot of lives and property.

CHRISTIAN BARTOLOME: OK, collect in three, two, one. Start.

SIEGLER: At this fire research lab in Riverside, California, a team of scientists and technicians lights a pile of dead wood shavings on fire. They're resting on a shelf in a 30-foot-long, 10-foot-high wind tunnel. The shavings are meant to mimic a dry forest floor. A few feet above them are freshly picked green shrubs, the live green trees in this simulated wildfire. The lab, it smells like campfire.

Turn on a little breeze through the tunnel, just like that, all that live green is suddenly up in flames. Now it's more like a bonfire, ashes falling everywhere.

DAVID WEISE: OK, what we have here is actually the fire's spreading really well on the surface with about 1 or 2-foot flames. And then that elevated canopy looks to be burning with flames on the order of eight to ten feet.

SIEGLER: The lead research forester here is David Weise.

WEISE: Yes, even though it's green, it's really burning quite well.

SIEGLER: No surprise, these are the plants that blanket the chaparral hills of Southern California and Arizona notorious for fueling some spectacular wildfires. But what Weise wants to know is, what are the precise conditions that turn this small fire into a potentially large one that would be almost impossible to control in the field?

WEISE: What we're trying to do here is conduct these experiments so that we can produce models, which can be used to perhaps predict what might happen under conditions that might be outside of a manager's experience.

SIEGLER: Weise says with improved models of fire behavior, that fire manager will have a better idea where to put resources to get out in front of the fire. For the past two months they've been conducting experiment after experiment here under all kinds of different wind speeds, humidity and types of fuel. Well, it turns out most of the fire behavior models in practice today are based on research conducted 40 years ago. And most of those are based on what a fire does in dead or dry fuels, like downed trees or brush and understory.

Tim Sexton is a former incident commander and crew boss who's now with the National Inter-agency Fire Center in Idaho.

TIM SEXTON: If you have very specific understanding of the live fuel moisture, that may make the difference in using a direct attack building a line immediately adjacent to the fire or in needing to back off to a ridge or some road but some distance from the fire to operate safely.

SIEGLER: Sexton says research like this that could help fire managers do their jobs better has never been so important. Firefighters are encountering more dangerous blazes as the west experiences larger and more intense fires due to drought and the spread of development in to the woods. Kirk Siegler, NPR News. Transcript provided by NPR, Copyright NPR.